import java.util.Scanner;

public class HomeWork03_07{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        
        System.out.print("please enter your score: ");
        int score = scan.nextInt();
        while(score > 100 || score < 0){
            System.out.print("data error, please enter your score again: ");
            score = scan.nextInt();
        }
        
        if(score >= 80){
            System.out.println("优");
        }else if(score >= 70){
            System.out.println("良");
        }else if(score >= 60){
            System.out.println("及格");
        }else{
            System.out.println("不及格");
        }
    }
}